Oceanography

3.2.1.Types of tide

About twice each month, lunar and solar tidal bulges are in-phase and experience constructive interference. Tidal bulges overlap and produce a very high, high-tide and a very low, low-tide. Bimonthly maximum tidal ranges are called spring tides. Spring tides result from the “straight” line arrangement of the Earth, Moon and Sun and occur during full and new moons. Similarly, twice each month lunar and solar tidal bulges are out-of-phase and experience destructive interference when high tides of lunar tidal bulges overlap troughs between solar tidal bulges. Minimal tidal ranges result. These tides are called neap tides. They occur during the first and third quarter moon, when the Moon is at 90° from the Sun relative to the earth.

Term to describle the phases of moon: Full moon means that the Moon is on the opposite side of the Earth from the Sun and the entire side of the Moon facing the Earth is illuminated in the night sky.

New moon occurs when the Moon lies directly between the Earth and the Sun. Because the Moon is on the daylight side of the Earth, there is no moon in the night sky during a new moon.

If the monthly trip of the Moon “around” the Earth is divided into quarters beginning with the new moon, the first and last quarter Moon occur when the Earth, Sun and Moon align to form a 90° angle. From the Earth, half of the Moon is illuminated, at the first and last quarter. It is called a quarter moon because it is seen at the first quarter and last quarter of the lunar orbit.

Waxing of the Moon describes the period between new moon and full moon. Each night more of the Moon is illuminated. Waning of the Moon refers to the period between the full moon and new moon. Each night less of the Moon is illuminated.